The goal of this research project is to understand the structure and function of DNA polymerases in normal and cancer cells. Using a combination of biochemical, immunological and genetic techniques, a comparative study on the molecular structure, the interaction of the enzymes with other components required for DNA replication and DNA repair will be carried out. These studies may produce some important clues related to the control of cell growth in hyperplasia and neoplasia. The specific aims of this project are: 1. Purification and examination of subunit structures of the high molecular weight DNA polymerase and mitochondrial DNA polymerase. 2. Preparation of antisera against purified mammalian DNA polymerase from normal and tumor cells for studies of the immunological relationships of the enzymes. 3. Biochemical and immunological comparisons of DNA polymerases from rat liver, regenerating rat liver and Walker 256 carcinoma cells. 4. Studies on the interactions of purified DNA polymerases from normal and tumor cells with other proteins required for DNA replication and DNA repair. 5. Search for temperature sensitive mutants of DNA polymerases in mammalian cells.